Method of improving flowing characteristics of coal



Patented May 13, 1930 WALTER EDWIN TRENT, OF NEW YORK,

PATENT OFFICE N. Y., ASSIGNOR TO TRENT PROCESS COR- PORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE METHOD OF IMPROVING BLOWING CHARACTERISTICS OF COAL N Drawing.

The invention relates to a method of improving the mobility or flowing characteristics of finely pulverized coal to enable such coal to be rapidly advanced from a point of storage to a zone of cumbustion.

The use of pulverized coal in boiler plants and the like is now looked upon with considerable favor, and in most of the present day operations such coal is advanced in a continuously moving stream or body by a suitable pump from a source of supply to a boiler or other zone of combustion. It is desirable to utilize as little pump pressure as possible in advancing such coal and yet at the same time feed the coal to a point of combustion at a sufficient rate of speed to insure an adequate operation of the boiler plant.

I have found that the speed of movement of the fine coal can be materially accelerated if this coal is heated and maintained at a critical temperature during its travel, below which temperature I have found the speed or movement of the coal appears to be comparatively sluggish.

I have discovered that if the finely pulverized coal, which may be of a fineness of 100 meshes per linear inch or finer, is heated to a temperature where vapors issue from the coal particles and is maintained at such a temperature, the speed of the coal during its movement is materially accelerated whereby the coal with a minimum pump pressure can be advanced in a minimum period of time from a source of supply to a zone of combustion. I have found that when the coal is at a gasifying temperature its mobility or flowing characteristics are materially increased, and I have also found that when coal is maintained at such a temperature itbehaves more or less as a liquid. The flow or speed of movement of the coal when heated to a temperature below its gasifying temperature is comparatively sluggish or slow.

In carrying out my invention I therefore heat the coal to a temperature where vapors are issuing from the coal particles and while this coal is moving under a pump or other pressure through a conduit or conductor I maintain the particles at a temperature suificient to cause a continuance of the gasifica- Application filed October 25, 1926. Serial No. 144,163.

tion of such particles thereby accelerating materially the speed of the moving coal particles.

In my process the coal may be introduced to a suitable vessel and there heated to a tem perature of say 200 C. From this vessel the finely pulverized coal is advanced by either pump or head pressure through a line or other conduit to be conveyed to the fire box of a This temperature will, of course, vary, de-

pending upon the distillation point of the coals undergoing transportation. Then again the conduits may, if desired, be insulated, and the initial heat given the coal if the insulation is an'etfective one, will prove sufficient to maintain the coal particles at the desired temperature during the time of their travel from a source of supply to a point of combustion.

I have found that the flowing characteristics of the coal are materially increased by this process particularly if the coal is in a finely pulverized state. I preferably use coal reduced to a fineness of 100 meshes per linear inch or finer, but obviously my process is not limited to coals of such a state of sub-division, this reference being made merely for the purpose of illustrating a preferred manner in carrying out my process. 7

I have likewise discovered that if a maximum rate of flow is to be obtained the coal particles must be subjected to a temperature at which gases are evolved. This is important inasmuch as I have discovered that if the particles are not heated to such a temperature their flowing or mobile characteristics are not nearly so pronounced as such characteristics are when the particles, are heated to a distillso I ing temperature. In fact, the speed of the particles is materially accelerated immediately after such particles begin to evolve gases.

This process is particularly useful in any 5 plant Where pulverized coal is being consumed, as it permits the coal particles to be advanced from a source of supply to a zone of combustion in a minimum amount of time and With a minimum pump or head pressure.

It will be furthermore understood that when the coal is brought to the temperature herein specified, air that would ordinarily be entrained in the voids or spaces between the particles of coal is driven out so that little or no air is present in the coal undergoing transportation.

Having thus described the invention, what I claim is:

1. An improved method for supplying pulverized coal to a combustion zone comprising introducing the pulverized coal to a suitable vessel and there heating the same to a temperature of approximately 200 0., advancing the pulverized coal while at this temperature and without substantial increase in temperature from said receptacle through a closed conduit to a zone of combustion.

2. An improved process for supplying coal to a zone of combustion comprising raising the powdered coal to that temperature at which gases begin to be evolved from the coal without raising the coal to such temperature as will effect coking thereof, advancing the heated coal through a conduit while maintained at substantially such temperature to the combustion zone.

3. An improved method for supplying powdered coal to a zone of combustion comprising initially raising the powdered coal to a temperature at which gases begin to evolve from the coal but below that at which any substantial coking will be effected, thence passing the coal while at such temperature through a conduit under pressure to a combustion zone and supplying sufficient heat to thecoal advancing through said conduit to maintain the same at the temperature to which it was initially elevated.

4. An improved method for supplying powdered coal to a zone of combustion comprising initially raising the powdered coal to a temperature at which gases begin to. evolve :from the coal but below that at which any substantial coking will be effected, thence passing the coal while at such temperature through a conduit under pressure to a combustion zone and supplying sufficient heat to the coal advancing through said conduit to maintain the same at the temperature to which it was initially elevated by circulating a heating medium about said conduit.

In testimony whereof I afiix my signature.

WVALTER EDlVIN TRENT. 

